I just had this same thing happen. I exported my files to an MP3 rough mix and when I opened the session again, everything was wiped. The vocal track still had some track information, (as in it was highlighted but empty), and I was able to see "Associated Audio Files" and recover it. All of the automation was gone. EZ Drummer midi data was also still available. Plug-in, levels, panning, etc were all still correct on the rest of the track, but the waves were gone. With all of my takes, it is impossible to rebuild. I had a bunch of muted tracks for alternate ideas, etc. I am hoping it was human error where I accidentally hit select all for the bounce and inadvertently deleted the files. As frustrating as that would be, it is better than thinking the software wiped the files. I just don't think that is what happened so I'm posting in case this becomes a recurring issue for all of us.